Re: Starting a driver within a driver...

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no, you can't pend the start irp. on a lot of OS variants, the pnp enum
lock is held and the pnp manager will synchronously wait for the start to
complete before starting the next device.

d

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"Ray Trent" <ratrent@xxxxxxxxxxxxx> wrote in message
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Can he just pend the start-irp for device 2 if device 1 isn't started yet,
and complete it when signalled? Seems like the rest of the system might
have a more "correct" view of the world in this case.

BTW, if there's no particular reason to have 2 separate .sys files, it's
sometimes much simpler to implement a unified multi-device driver (i.e. 1
.sys file that handles multiple devices of different types), because a lot
of the inter-device dependencies can be handled with global variables and
internal function calls rather than more complex signaling methods.

Eliyas Yakub [MSFT] wrote:
Device #2 depends on Device #1.

Can I do something with dependencies to ensure the OS starts device #1
first, then device #2?


There is no system provided way to control start order of two devices.


Assuming that cannot be done with dependencies, I
need #1 to signal #2 to start--and #2 to start only if #1 is already
started. Then the order in which the OS tells the drivers to start won't
matter--while the dependency effectively holds.



You can devise your own signalling technique. I have used callback
objects (ExCreateCallback) in my drivers to control load order
dependencies of two independent drivers. If you need sample code, send me
an email note.

The way I see you solving the problem is that if #2 is started before #1
then #2 would complete the start-irp with STATUS_SUCCESS, but wouldn't
really initialize the device until #1 starts and signals #2. Correct? I'm
not sure all the thing that PCI bus driver does when it receives the
start-irp, but wouldn't you have any problem if start-device of #2 is
handled by the pci bus before #1?



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